Antibodies are a major line of defense against viral infections. However, little is understood as to the mechanisms of antibody neutralization and recognition. There has been a lot of discussion in the literature as to whether antibodies can induce gross conformational changes in the virion capsid. Some studies suggest that such changes cause viral neutralization whereas others claim that aggregation is sufficient. We hope to finally determine the existence and role of antibody induced conformational changes. Peptide vaccines are notoriously bad at inducing neutralizing antibodies in animals. A notable exception is foot and mouth disease virus (FMDV) where a large flexible loop is the dominant antigenic feature. By studying what aspects (e.g. shape and charge) of the antigen are important in antibody recognition, it may be possible to improve synthetic vaccines. Some monoclonal antibodies to human rhinovirus 14 may bind bivalently to the surface of a virion. To date, there has not been the examination of an antibody bound in such a way. This structure will help define the extent of flexibility between domains of antibodies. To accomplish the above goals, antibody neutralization will be examined structurally at several levels. The structure of Fab17-IA will be refined and further examined in context of the image reconstruction of the Fab17-IA/HRV14 complex. Structural studies will be carried out on the crystals of escape mutants and of the Fab17-IA/HRV14 complex. Structural studies will be carried out on the crystals of escape mutants and of the Fab17-IA/HRV14 complex. The extent of Fab contact and importance of individual residues will be tested by site-specific mutagenesis. Antibody bivalent attachment and conformational changes will be examined by further electron microscopy studies and the structure of the Fab17-IA/HRV14 complex.